On a conference call with Gov. Chris Christie’s most loyal donors a few nights ago, his brother, Todd, pressed for last-minute cash to pay for the governor’s inauguration, a daylong fete ending on Ellis Island.

Then the governor himself came on the line, trying to convince his listeners that he was moving beyond the George Washington Bridge scandal and getting back to work, according to two participants.

The next day, state investigators sent 20 subpoenas to his inner circle and the inquiry widened.

This was supposed to be a season of triumph and celebration for the governor of New Jersey — a chance to bask in his landslide re-election victory in a Democratic state, embark on a European tour to bolster his foreign policy credentials and emerge as the modern face of a Republican Party desperate to win back the White House.

Now, the foreign trip is in limbo as Mr. Christie tries to rebuild his credibility. His biggest political assets, his personality and spontaneity, have been all but absent as he evades reporters’ questions and holds few public appearances. And Republicans around the country, including those who saw him as their party’s most compelling candidate for president in 2016, are calling in with advice, sobering in its candor.

Party leaders are urging the governor to let go of a trademark Christie trait: his fierce loyalty to old friends and high school classmates who have risen with him in state government. It is time, they counsel, for him to recruit a more nationally savvy political team that can take him beyond Trenton to Washington. Fueling such concerns, new allegations arose on Saturday that top Christie aides had used Hurricane Sandy recovery money as a political weapon against the Democratic mayor of Hoboken, N.J.

The scandal could still fade, and Mr. Christie remains popular with many voters in his home state. But a recent episode underscored how things have changed: The governor had envisioned traveling to South Carolina this spring to campaign for Senator Lindsey Graham, who faces a conservative primary challenge. Mr. Graham, in an interview last week, said Mr. Christie’s presence would be an unwelcome distraction.

“If you brought him in South Carolina today, what would we be talking about?” Mr. Graham asked. “We’d be talking about him.” The billionaire Kenneth G. Langone, Mr. Christie’s most devoted fund-raiser and loudest cheerleader, got in touch with him in recent days. Mr. Langone said he told the governor that he must be smarter about those who surround him.

“I conveyed the importance of the decisions he makes about the people around him and their qualification and their competence, including common sense,” said Mr. Langone, who called the politically motivated closure of lanes onto the George Washington Bridge “beyond the pale.”

“It upset the hell out of me,” he said.

Mr. Christie has told friends and contributors that he can weather the slings and scrutiny, even as he complains about what he sees as “piling on” by his enemies and a once-admiring news media, according to people told of his thinking, who spoke on the condition of anonymity because they did not want to be associated with comments that could upset the governor or his aides. Mr. Christie has leaned hard on his wife and brother for advice, in long, searching conversations. (The governor could not bring himself to watch the traffic jam-themed parody of “Born to Run” sung by his idol, Bruce Springsteen, on “Late Night With Jimmy Fallon,” though he was told by his college-age son, Andrew, that it was funny.)

Inside Mr. Christie’s inner circle, advisers are disputing public opinion polls, which show a noticeable drop in his popularity and job approval rating, saying that his previous sky-high numbers were inflated by election-year advertising.

Several Republican governors said they were heartened by Mr. Christie’s efforts to address the controversy head-on. So long as he is telling the truth and was not personally involved in the shutdown in Fort Lee, they said, Mr. Christie will remain a major force within the party.

“I thought he handled the situation correctly,” Gov. Terry Branstad of Iowa said. Asked if he would campaign alongside Mr. Christie this year, he said: “I’m not at all afraid to invite him.”

But there may be complications ahead. With investigators blanketing the Christie administration with subpoenas late last week, new revelations could surface and force the governor to respond further.

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Gov. Christie must be smart about those who surround him, Republican Party leaders say.CreditPeter W. Cross for The New York Times

The Republican Party cannot afford serious damage to Mr. Christie: As the newly installed chairman of the Republican Governors Association, he is responsible for helping to raise $85 million this year to assist the party’s candidates for governor.

Of all the new realities that Mr. Christie must confront, perhaps the most humbling is a sense of losing the momentum that surrounded him just a few months ago. Last year, the governor’s staff had begun building up his foreign policy bona fides, quietly reaching out to Brian H. Hook, a Republican foreign policy expert who worked at the United Nations for President George W. Bush, and started planning his international trip.

Asked whether the trip is still on, Mr. Christie’s adviser William J. Palatucci responded: “It’s all to be determined.”

Inside the Republican Party, the once constant talk of Mr. Christie’s path to the White House has quieted. “I think anything about a 2016 deal, at this point, is on the back burner,” said Ray Washburne, the finance chairman of the Republican National Committee.

Foes, sensing vulnerability, are now emboldened to take on Mr. Christie. Democrats have waged a campaign of mockery against him, which will climax this weekend in Florida, where the party’s chairwoman, Representative Debbie Wasserman Schultz, will follow him around the state, denouncing Mr. Christie outside of fund-raisers he is scheduled to attend on behalf of Gov. Rick Scott.

“He’s going into battle with armor that’s now a little bit dented,” said Steve Munisteri, the chairman of the Republican Party of Texas. Potential backers for a presidential run, he added, “now have pause.”

Whatever the lasting damage to Mr. Christie’s political brand, Republicans said, the puzzling traffic imbroglio has laid bare his weaknesses: a stubborn insularity, the absence of a national infrastructure and a tendency to be flip and glib, which haunted him at the start of the bridge scandal.

Despite his ambition, he has a remarkably small team of advisers in New Jersey: Mr. Christie, for example, has no designated representative in Washington, hampering his efforts to coordinate the expressions of support that are essential in a crisis.

“I think he needs to build a national political team,” said Bobbie Kilberg, a major Republican fund-raiser based in Northern Virginia, who noted that she is “sticking with Mr. Christie” if he runs for president.

Mr. Christie started reaching out to seasoned Republican hands over the past week, including a former Republican National Committee chairman, Ken Mehlman, and Karl Rove.

As the scrutiny of Mr. Christie intensifies, even routine obligations like the Florida fund-raising swing are taking on an outsize significance. Christie supporters are determined to show that the governor is still a big attraction; Mr. Langone, a founder of Home Depot, said the reception planned for Sunday at his Palm Beach home had drawn “huge interest.”

But a flap has erupted in Republican circles, as Mr. Scott, who faces a tough bid for a second term, does not seem eager to be seen in public with Mr. Christie: The two have no plans to campaign together, and their staffs have closely guarded information about the fund-raising events.

Some wondered openly about the wisdom of Mr. Christie mingling with Florida donors as the investigation of his administration widens.

Michael Steele, a former chairman of the Republican National Committee, told an audience at a Palm Beach luncheon on Friday that the governor should have stayed home to “focus on the people of New Jersey.”

“I probably would have canceled that if I were in his position only because, guess what happened yesterday?” he said. “They dropped 20 subpoenas on him, and so now that’s baggage that’s going to come into the conversation he’s having here.”

Jeremy Peters and Ravi Somaiya contributed reporting.

A version of this article appears in print on , Section A, Page 1 of the New York edition with the headline: G.O.P. Advice for Christie: Pick a Better Team. Order Reprints | Today’s Paper | Subscribe